The present invention is in the field of apparatuses for applying a longitudinal stress on a running material of indefinite length. More specifically, the present invention relates to a tension control device associated with a cable drum, the device for applying a clamping drag on a running wire rope, cable or line being wound onto the drum.
In the operation of a crane, wire rope or cable wound on hoist drums is used in the lifting of heavy loads, and periodically must be replaced. To insure proper installation of the wire rope or cable, the rope or cable must be tight and tracking properly on the hoist drum. Usually, this is done utilizing manually operated tensioning devices. Further, the boom and/or cable needs to be extended and a load placed on the block in order to assure the cable is tight and tracking properly on the hoist drum.
Various tensioning devices have been used to apply tension to cable to be installed. Included among these are Alquist, U.S. Pat. No. 5,009,353 which describes a device attached to a wire cable to maintain tension on the wire for proper spooling of the cable on a winch drum. Another example of a wire tensioning device is Laky, U.S. Pat. No. 4,227,678. Laky discloses a device in which the cable is wound through the gear train to the traction roller which rubs against the cable as it passes in and out of the hoist. Still another example is Wolfe, U.S. Pat. No. 3,881,647 disclosing an anti-slack device for maintaining constant tension of wire ropes while being unreeled or re-reeled.
Further, Shutt, U.S. Pat. No. 4,023,744 discloses a device for maintaining tension in a cable while winding on or off a power driven cable drum. Koch, U.S. Pat. No. 5,368,212 discloses a device for maintaining tension in a cable while winding on or off a power driven cable drum while fed in a predetermined direction to the automatic cable processing machine.
Although theses devices may be useful each for its intended purpose, it would be beneficial to have an alternative device that does not have moving parts. Those apparatuses comprise tensioning devices that have moving parts, and even include drive motors.
The present invention is a device for providing tension to running stock, cable or line (e.g., wire rope) as it is being wound onto a drum. More specifically, the present wire rope tensioning device provides a clamping drag on a length of running stock, cable or line as it is being wound onto the drum. The present device has no moving parts and its preferred use is to tension new cable or wire rope as it is being initially wound onto a drum.
The present wire rope tensioning device comprises a tubular housing in two longitudinal halves. Installed inside the tubular housing is a removable inner sleeve, also in two halves. The each inner sleeve half lines the inside side surface of a tubular housing half. The sleeve has an axial bore passing through it, centered along the axis of the inner sleeve. The axial bore receives a length of the cable or line to be tensioned. A clamp means provides for clamping the housing halves and sleeve around a length of cable or line received in the axial sleeve bore to squeeze the length of cable and impart a clamping drag on the cable or line as it runs through the device while being wound onto the drum.
The tubular housing is comprised an open cylinder of two separate longitudinal halves. The tubular housing is constructed of a material suitable for its application, such as steel or other metal or appropriate material. The tubular housing halves have a first set of adjacent edges and a second set of adjacent edges. A means for joining the housing halves together is disposed along each set of adjacent edges. The inner diameter of the tubular housing ranges from about 1 inch to about 2 inches. Typically, a tubular housing having an inner diameter of about 1xc2xd inch will be useful for most applications for tensioning running stock (cable, line, rope of various types) having diameters ranging from about {fraction (3/16)} inch to about 1 inch.
The tubular housing has a length ranging from about 8 inches to 18 inches. Typically, a tubular housing having a length between about 10 inches to 12 inches will be satisfactory for most applications.
A hinge means is a suitable mechanism for joining the tubular housing halves together along a first set of adjacent edges. A clamp means is a suitable mechanism for joining the housing halves together along the second set of adjacent edges. Alternatively, a clamping mechanism may be used to join the tubular housing halves together along both sets of adjacent edges. Hinge and clamp mechanisms suitable for practice in the present invention are known to and readily selectable by one of ordinary skill in the art. For example, a clamp means can be a simple screw-latch and catch combination, where a catch is posed proximate the adjacent edge on a first housing half, and a latch assembly is posed proximate the adjacent edge of the second housing half. When the latch assembly is engaged with the catch, the combination may be reversibly screwed together to provide for a clamping relationship between the two halves of the tubular housing.
An inner sleeve is closely received in and lines the interior surface of the tubular housing. The removable inner sleeve is comprised of two longitudinal halves, with each inner sleeve half mated to a tubular housing half. The inner sleeve has an axial bore through the length of its axis. The axial bore has a diameter ranging from about {fraction (3/16)} inch to 1 inch. The axial bore provides a channel for receiving and compressing a running stock to be wound onto the drum when the stock is disposed between the halves of inner sleeve. Running stock can be cable, line or rope of various compositions, including wire rope.
The inner sleeves are fabricated from a frictional material. The material is frictional in that when the sleeve is compressed about the running stock, drag or tension is imparted to the running stock in the opposite direction of its passage through the inner sleeve. The inner sleeves are fabricated from a frictional material appropriate for the composition of the running stock. Such frictional materials include steel, brass, and ultra high molecular weight polyethylene and other materials as may be appropriate for the running stock and the tension to be imparted to it.
A fastening means fixes or holds each inner sleeve half to the interior surface of its respective tubular housing half. A variety of such fixing means are known in the art. An appropriate such fixing mean is readily selectable by the ordinary skilled artisan for practice in the present invention. For example, a suitable fixing means is a threaded fastener passing through the inner sleeve half and engaging its respective tubular housing half, or vice versa. Alternatively, a threaded fastener can pass through the inner sleeve half and the tubular housing half to engage a nut at the outer surface of the tubular housing half and fix the sleeve halves in place. As a further alternative, a detent partially closing the end of the tubular cylinder of the housing in the direction of travel of the running stock can hold the sleeve halves in place in the housing.
The present invention imparts drag or tension to the running stock by the clamping action of the housing compressing the inner sleeve halves against the running stock as the stock is drawn through the tensioning device. The clamping action of the housing is accomplished in the tensioning device by drawing the two tubular housing halves together against the inner sleeve. The drawing of the tubular housing halves together is accomplished by the combined action of a hinge means and a clamp means. The hinge means is disposed along a first set of adjacent edges of the tubular housing halves, which allows the halves to be closed to form a substantially circular cross section. The clamp means is disposed at the second set of adjacent edges of the tubular housing halves, and is used to draw housing halves together against a resistance to closure caused by the combination of a length of running stock received in the axial bore of the inner sleeve between the sleeve halves. Alternatively, clamp means may be disposed along both the first and second sets of adjacent edges and operable to provide the clamping action of the tensioning device for closing the housing halves and compressing inner sleeve halves around the running stock received in the axial bore.
An anchor means is fixed to the outer surface of the tubular housing for mounting the housing in a position against movement. Such anchors may be accomplished as anchoring rings fixed (e.g., by welding) to the outer surface of the housing. Anchoring rings may be accomplished using a section of xc2xe inch i.d. schedule 40 steel pipe. The anchoring means may be fixed to one or to both of the tubular housing halves.
In use, the wire rope or cable is placed in the axial bore of the inner sleeve of the wire rope tensioning device. The housing halves are then closed around the wire rope and a compressive force is applied to the cable by tightening the housing clamp(s). The tensioning device is anchored in a suitable location, and installation of the cable onto the drum can proceed. The housing halves, hinge means and clamp(s) are disposed to compress the inner sleeve halves against the wire rope or cable received in the axial bore of the inner sleeve. The clamping action of the device causes resistance to the passage of the cable through the housing, thereby tensioning the cable as it is drawn through the housing and wound onto the drum. The inner sleeve halves are each mechanically secured to the inner surface of their respective housing halves. The inner sleeve halves are removable and replaceable. The axial bore of the inner sleeve is selected to compliment and compressibly engage the gauge of cable to be wound onto the drum.